Direct-print light-developable silver halide emulsion containing cyclic dioxide or selenone as sensitizer

ABSTRACT

A photographic emulsion of the silver halide directprint lightdevelopable type containing cyclic compounds of the general formula:   D R A W I N G

United States Patent [191 Walters et al.

I DIRECT-PRINTLIGHT-DEVELOPABLE Robert E. Ileeks, Penfield; Donald P. Sullivan, Rochester, all of NY.

[73] Assignee: Xerox Corporation, Stamford,

Conn.

[22] Filed: Jan. 2, 1973 [2]] Appl. No.: 320,422

52 U.S.Cl 96/107,96/108, 96/109 51 1111.01 G03c 1/28 [58] Field ofSearch ..96/l07,108,109

[56] References Cited UNITED STATES PATENTS 4/1970 Sincius 96/108 7/1971 Sincius 96/108 Nov. 19, 1974 3,649,289 3/1972 Hiller 96/107 Primary Examiner-Ronald H. Smith Assistant Examiner-Won H. Louie, Jr.

Attorney, Agent, or Firm-James J. Ralabate; David C. Petre; George J. Cannon [5 7] ABSTRACT A photographic emulsion of the silver halide directprint light-developable type containing cyclic compounds of the general formula:

v vvherein X'fiia' be S or Se; and hydrogen and lower alkyl substitution products thereof. Optimum results may be obtained by addition of iodide, gold and silver thiocyanate sensitizers.

8 Claims, No Drawings 1 DIRECT-PRINT LIGHT-DEVELOPABLE SILVER HALIDE EMULSION CONTAINING CYCLIC DIOXIDE OR SELENONE AS SENSITIZER BACKGROUND OF THE INVENTION This invention relates in general to photographic emulsions. More specifically, the invention concerns photographic emulsions of the direct-print lightdevelopable" type.

The term aireegrrmart araspatte "retains background area and re-exposure of the area upon which the initial imagewas formed. Direct-print lightdevelopable materials are distinguished from develop-' ing-out emulsions in that they do not require a wet development treatment, such as a multi-step chemical development after initial exposure to produce a visible image. While the direct-print light-developable materials of this invention may be used for ordinary photographic purposes, they are particularly sensitive to a high intensity beam of light or other electromagnetic radiation and are, therefore, especially useful in high speed recording such as oscillographic recording and the like.

Direct-print. light-dev elopable type materials are today in general use for recording of oscillographic traces. However, the direct-print light-developable materials of the prior art are not entirely satisfactory for this recording purpose for a number of reasons. For example, it is generally true that the prior art materials which exhibit high sensitivity to an exposure of short duration to a high intensity beam tend to exhibit a correspondingly low degree of background stability. The latensification' procedure for these materials is highly critical and accordingly is exceedingly difficult to carry out. The latent image may be entirely lost during the latensification operation where the background darkens too rapidly. In other cases, a phenomenon known as reversal may occur, this being a darkening of the background which proceeds at a more rapid rate than darkening of the image trace. In these situations, the trace may be temporarily or permanently obscured. Conversely, materials which exhibit a high degree of background stability tend to exhibit a correspondingly low degree of sensitivity to the recording beam and, thus, the minimum exposure time is far above that desired for use in modern recording instruments.

is not as stable when exposed for prolonged times to daylight or normal room lighting as would be desirable. Upon prolonged exposure to ordinary illumination, the background darkens and the image regresses depending upon the viewing conditions which reduces the ratio between background and image density.

On occasion it is desirable to make a truly permanent record of an oscillographic trace. In this circumstance. it is desirable to develop the usual direct-print liglitdevelopable emulsion either before or after latensification by chemical developing-out techniques. Many conventional direct-print light-developable emulsions require special developing materials and procedures. Preferably, a direct-print light-developable emulsion used in an oscillographic recorder should be developable by the usual direct-print light-developable techniques or alternatively, by means of a chemical developing-out process.

Different direct-print light-developable materials produce image traces and background areas of varying colors. Typically, the image trace may be developed as a brown or'blue-grey line. The background areas which would preferably-remain white often acquire a uniform color, typically, pink, brown or blue. Preferably, there should be good contrast between. the trace and backgrounds both in density and in color to permit convenient and accurate examination and evaluation of the trace.

It is also desirable to have access to the information recorded on the material as rapidly as possible. The access time is the period of time which elapses between the imagewise exposure and the first appearance of the recorded information in response to latensification.

Thus, there is a continuing need for improved directprint light-developable materials having improved sensitivity, stability and appearance characteristics.

SUMMARY OF THE INVENTION It; is, therefore, an object of this invention to provide a direct-print light-developable emulsion overcoming the above-noted disadvantages.

Another object of this invention is to provide a novel light sensitive composition. t

Another object of this invention isto provide a more sensitive dry process for the reproduction of images.

Still another object of this invention is to provide a photosensitive emulsion which may be developed either by direct-print light-developable techniques or by chemical developingout techniques.

Still another object of this invention is to provide an improved direct-print light-developable emulsion which possesses both a high degree of photosensitivity and a high degree of background stability under general latensification.

Another object of this invention is to provide a photosensitive emulsion which provides relatively improved access time.

A still further object of this invention is to provide a direct-print light-developable emulsion resistant to erably, the emulsions also contain iodide, gold and silver thiocyanate.

Good results have been obtained using from about 0.02 to 20.0 mole percent of cyclic compounds of the formula given above based on moles of silver in the silver halide grains. Approximately 0.01 to 25 mole percent iodide is added to the emulsion. Additional benefits primarily in reduced access time and increased image contrast results from the addition of from about 0.001 to about 1.0 mole percent gold to emulsions containing compounds within the formula given below. Optimum results are obtained with the addition of from about 0.l to 25 mole percent silver thiocyanate based on the silver in the silver halide grains. The use of silver thiocyanate is disclosed in our copending application Ser. No. 125,816, filed Mar. 18, 1971 the disclosure of which is incorporated herein by reference. The sensitizers may be added in any suitable form. The silver thiocyanate is added in the form of a gel suspension. Typically, gold and iodide are added as water soluble complexes or salts in water. However, this is not necessary. For example, some ingredients may be added as solids or in other solvents such as acids, bases or water misci ble organic solvents.

As is further pointed out in the Examples below, theuse of iodide alone provides images having low contrast and low sensitivity. The addition of compounds of the general formula to the emulsion containing iodide im-' proves contrast; that is, the difference in density between the image area Dmax and the density of the: background areas Dmin is greater. The difference be tween Dmax and Dmin is known as A D. It also improves sensitivity which increases the speed at which images may be recorded. Further, the addition of gold to the emulsions containing cyclic compounds of the general formula given above and iodide improves the access time. Optimum image quality is achieved by made by first forming silver chloride and then converting substantially all of the silver chloride into a mixed crystal of predominantly silver bromide by adding a 501- uble bromide salt to the emulsion. Gelatin is the conventional binder for photographic emulsions. However,; any other suitable binder, such as polyvinylalcohol, may be used if desired. Ordinarily, this layer should bei no greater than about 25 microns in thickness. For op-: timum results, the layers should contain about three grams of elemental silver per square meter of coated; emulsion. The emulsion layer may contain additional ingredients to enhance, synergize or otherwise modify its characteristics, as desired. Typical silver bromide emulsions are described in Photographic Emulsions," E. 1. Wall, American Photographic Publishing Co., Boston (1929) and in U.S. Pat. No. 3,249,440.

Silver thiocyanate is added to the emulsion in the form of a suspension, preferably about 0.6 mole AgCNS per liter of a gelatin suspension. The suspension is formed by adding silver nitrate to potassium thiocyanate in water. The precipitateis dispersed in a gelatin binderfSince the silver thiocyanate formed is light sensitive, the precipitation and subsequent process steps should be carried out under safelight conditions. The silver thiocyanate is added after the silver halide grains have been formed.

The iodide may be added in the form of any compound which will furnish iodide ions to the suspension and may be water soluble or insoluble. Typical compounds include lead iodide, silver iodide, alkali metal iodides, ammonium iodide, calcium iodide and barium iodide.

The gold may be added in the form of water soluble compounds such as ammonium aurothiocyanate', potassium aurothiocyanate, sodium aurothiocyanate, aurous thiosulfates, alkali metal aurous sulfates, chlorauric acid and alkali metal halides complexed with auric trihalides.

The iodide and gold are also added after the silver halide grains are formed. It is believed therefore that the sensitizers are primarily present on the surface of the silver halide grains. it is also believed that whether the gold is added to the emulsion in the auric or the aurous form that it is converted to or remains aurous because of the presence of thiocyanate. The sensitizers within the general formula given above are also added after the silver halide grain has been formed. The sensitizers are added along with the iodide, bromide and the dioxide.

DESCRIPTION OF PREFERRED EMBODIMENTS The following Examples in the Table further specifically define the present invention with respect to particular sensitizers and the amounts thereof used in the direct-print light-developable emulsions of this invention. All percentages used are mole percent per mole of silver in the silver halide grains unless otherwise indicated. The Examples below utilizing sensitizers within the ranges described above are intended to illustrate various preferred embodiments of the direct-print light-developable emulsions of the present invention.

A gelatino-silver halide emulsion for use in the following Examples with different amounts of different sensitizers is prepared as follows: An aqueous solution of silver nitrate is added to an aqueous gelatin solution .of potassium chloride in such a manner that there is bromide is added. The emulsion is then coated onto a substrate to obtain a layer having about three grams of elemental silver per square meter.

The direct-print light-developable emulsions thus produced in each Example are tested by exposing in an Edgerton, Germeshhausen and Grier Mark VII Sensitometer at microseconds exposure time. The test strips are exposed through a \/2 stepwedge. After exposure'the test strips are latensified for about minutes under General Electric Cool White Fluorescent lamps at an illuminational level of about 50 foot canemulsion layer to synergize, enhance or otherwise modify its properties. For example, sensitizing dyes. various finishing aids such as formaldehyde, surfactants. surface active agents such as saponin, humectants such as fl 5 glycerin, stabilizers such as 7-hydroxy-5-methyl-l,3,4-

' i TAELE mwmhmfl EXAMPLE NO.

1 2 3 4 5 6 Tctrahydro- [AgSCNl [AuSCN] [1] Access Time AD thiophcnc-l, Seconds l-dioxide 1 0.00 0.00 0.00 5.60 5 0.21 11 0.0198 0.00 0.00 5.60 7 0.22 111 00198 0.00 0.00 5.60 10 0.24 1v 1.98 0.00 0.00 5.60 8 0.31 v l9.8 0.00 0.00 5.60 9 0.20 v1 0.00 8.0 0.03 5.60 6 0.22 1 1 W 09128 8.0 0.03 5.60 4 0,22 v111 0 198 8.0 0.03 5.60 4 0.32 1x 1.98 8.0 0.03 5.60 5 0.36 x 19.8 8.0 0.03 5.60 3 0.26

2,5-dihydro- [AgSCN] [AuSCN] [1] Access Time AD thiophene- 1, Seconds l-dioxide x1 1.98 8.0 0003 5.60 4 0.34

3-methyl- [AgSCN] [AuSCN] {1] Access Time AD tetrahydro- Seconds thiophene-l l-dioxide x11 1.98 800 0.03 5.60 6 0.31 3-methyl-2, [AgSCN] {AuSCNl [I] Access Time AD S-dihydro- Seconds thiophened, l-dioxide As indicated by the above table, outstanding results H :triazoindolizine, matting agents, etc., may be used in are obtained with a direct-print light-developable emulthe emulsion layer. sion sensitized with the sensitizing agents of the present Other modifications and ramifications of the present invention. In the above table columns 1 through 4 indiinvention will occur to those skilled in the art upon a cate the mole percents of the cyclic compounds listed, 5 reading ofthe present disclosure. These are intended to silver thiocyanate, gold and iodide. respectively. The be included within the scope of this invention. fifth column gives the access time which is the amount What is claimed: of time required to produ ce a jfib i lnagt UPOII latenl. A photosensitive direct-print light developable sification. The sixth column gives the density difference emulsion comprising silver halide grains, a binder, io- Which indicates contrast between the image and back- 40 dide and a cyclic compound having the general ground. formula:

The above test results were obtained using relatively "MLMM small samples of photographic emulsion. When scaled up to production size quantities, it has been found that the optimum concentration of silver thiocyanate is about one-fourth that of the laboratory scale optimum. 2K The increase in sensitization obtained with larger 0 0 batches is believed to be caused by a number of vari ables which have not been duplleated m laboratory wherein X is seiected froni the g roup consistiiig of S- Scale apparatus For e p e the f lP p i e y and Se; and hydrogen and lower alkyl substitution Changes the average p f 511e, Pamele l products thereof; said cyclic compound being present tion and r1pen1ng cond1t1ons caused by d1fferences in i an u t ff ti t sensitize s id emulsion. agitation and in heating and Co ng y les between 2. The emulsion of claim 1 wherein there is included large and small batches. Further, it is believed that silf b t ()1 t b t 25 ol percent iodide based ver thiocyanate reacts with the surface of the silver halo the m les of silver in the silver halide grains. ide particles. Accordingly, the surface area available to 3, Th lsi of claim 1 wherein there is also inthe silver thiocyanate affects this reaction. Sensitizal d d from about 0,0] to about 25 percent iodide and tion will depend. therefore, on gel concentration, temfrom about 0.001 to about 1.0 mole percent gold based peratures and ripening conditions and also on the partion the moles of silver in the silver halide grains. cle size of the silver halide when the silver thiocyanate 4. The emulsion of claim 1 wherein there is included is added. The preferred quantity of silver thiocyanate from about 0.5 to about 9.0 mole percent silver thiocyfor large scale lots is about 2 mole percent based on the anate, about 0.4 to about 10 mole percent iodide and moles of silver in the silver halide grains. about 0.01 to about 0.1 mole percent gold based on the Although specific components and proportions have moles of silver in said silver halide: grains.

been described in the above Examples, other suitable materials, as listed above, may be used with similar re-. sults. In addition, other materials may beadded to the 5. The emulsion of claim 1 whereinsaid compound is selected from the group consisting of tetrahydrothiophene-l, l-dioxide; 2,5-dihydrothiophene-1,1-dioxide;

and

wherein X may be S or Se; and hydrogen and lower alkyl substitution products thereof.

8. The emulsion of claim 7 wherein said compound is selected from the group consisting of tetrahydrothiophene-l, l-dioxide; 2.5-dihydrothiophcne-l.l-dioxide; 3-methyltetrahydrothiophenel l -dioxide and 3- methyl-2,5-dihydrothiophene-l, l-dioxide.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION .Patent No. 4 6 Dated N r 19, 1974 Inventor) David W. Walters, Robert E. Heeks, "Donald P. Sullivan It: is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

I Cok];1;um'1c 15, Table, gxemple X, under "access time",

" s oul read Signed and sealed this 14th day of January 1975.

(SEAL) Attest:

McCOY M'. GIBSON JR. Attesting Officer c. MARSHALL DANN Coumiaaioner of Patents USCOMM-DC 603764 09 FORM PO-1050 (10-69) u.s. sovnuunu mm'ms omc: nu o-au-su. 

1. A PHOTOSENSITIVE DIRECT-PRINT LIGHT DEVELOPABLE EMULSION COMPRISING SILVER HALIDE GRAINS, A BINDER, IODIDE AND A CYCLIC COMPOUND HAVING THE GENERAL FORMULA:
 2. The emulsion of claim 1 wherein there is included from about 0.01 to about 25 mole percent iodide based on the moles of silver in the silver halide grains.
 3. The emulsion of claim 1 wherein there is also included from about 0.01 to about 25 percent iodide and from about 0.001 to about 1.0 mole percent gold based on the moles of silver in the silver halide grains.
 4. The emulsion of claim 1 wherein there is included from about 0.5 to about 9.0 mole percent silver thiocyanate, about 0.4 to about 10 mole percent iodide and about 0.01 to about 0.1 mole percent gold based on the moles of silver in said silver halide grains.
 5. The emulsion of claim 1 wherein said compound is selected from the group consisting of tetrahydrothiophene-1, 1-dioxide; 2, 5-dihydrothiophene-1,1-dioxide; 3-methyltetrahydrothiophene-1,1-dioxide and 3-methyl-2,5-dihydrothiophene-1, 1-dioxide.
 6. The emulsion of claim 1 wherein said compound is present in an amount of from about 0.02 to about 20 mole Percent based on the silver in the silver halide grains.
 7. A photosensitive direct-print light developable emulsion comprising silver halide grains, a binder, from about 0.01 to about 25 mole percent iodide, from about 0.001 to about 1.0 mole percent gold, from about 0.5 to about 9.0 mole percent silver thiocyanate, and from about 0.02 to about 20 mole percent of a cyclic compound having the general formula:
 8. The emulsion of claim 7 wherein said compound is selected from the group consisting of tetrahydrothiophene-1, 1-dioxide; 2, 5-dihydrothiophene-1,1-dioxide; 3-methyltetrahydrothiophene-1,1-dioxide and 3-methyl-2,5-dihydrothiophene-1, 1-dioxide. 